One of the world's biggest cities is opening its doors to Uber — under certain conditions

A photo illustration of the logo of the ride-hailing app Uber on a smartphone over a reserved lane for taxis in a street in Madrid. Thomson Reuters The mayor of Sao Paulo, South America's largest city, laid out regulations on Tuesday to allow the use of Uber and other ride-hailing apps in exchange for a mileage fee.

Mayor Fernando Haddad plans to formalize the decision with a decree Wednesday, overriding attempts by city-council members to ban Uber and other apps they accuse of unfairly competing with licensed taxis.

Under the decree, Brazil's congested business hub will charge an average fee of 10 centavos ($0.03) a kilometer for drivers working with Uber and its newly arrived Spanish rival Cabify, the mayor's office said, according to Reuters.

The city — which as of 2013 had a population of about 11 million people and a metro population of nearly 19 million — expects to raise about 40 million reais ($11.5 million) a year with the measure, said Ciro Biderman, head of innovation for the development agency SP Negocios, which designed the new regulations.

Despite the imposition of fees, the opening offered to Uber inspired anger among Sao Paulo's taxi drivers. Irate cab drivers blocked a major artery during the evening rush hour, and television footage showed a crowd pounding on the windows of a black car with tinted windows, which fit the profile of a standard Uber vehicle.

Uber called the mayor's decision "the first step toward guaranteeing that apps intermediating travel with technology have a place in the city." Cabify declined to comment.

The Sao Paulo mayor's openness to Uber differs from other countries and cities in the region where the ride-hailing app and governments have clashed over Uber's operations.

A taxi driver in front of the Santos Dumont airport during a protest against the Uber in Rio de Janeiro on April 1. REUTERS/Ricardo Moraes